A display device displays an image by letting a display panel selectively transmit light from a backlight. If the luminance of the backlight can be controlled for each predetermined area in this type of display device, the display device has an advantage in terms of the image quality. For example, the contrast of an image can be improved.
The above control of the backlight may be realized by, for example, providing a plurality of light guides facing different areas of the display panel, and a light source which supplies light to each of the light guides, such as a light-emitting diode, on the rear surface side of the display panel. However, in this case, for example, the thickness of the display device is increased since the light-emitting diodes need to be stacked on the display panel. Thus, various problems may occur.
One of embodiments described herein aims to provide a display device capable of improving the image quality by controlling the luminance of a backlight for each portion, or to make the display device thinner.